ω Centauri, the largest globular cluster of our Milky Way, is an outstanding object in many aspects. Studies on the red giant branch (RGB) revealed a large spread in iron abundance, which ranges from [Fe/H]∼-2.0 to -0.4 dex and the existence of multiple sub-populations that do not only differ in their element abundances but also in their spatial and kinematic distributions (e.g. Norris et al. 1997). Furthermore more recent photometric studies suggested the existence of an age spread between these subpopulations (e.g. Hilker & Richtler 2000).

We show that contrary to what is expected from 1D stationary model atmospheres, 3D hydrodynamical modeling predicts a considerable influence of convection on the spectral properties of late-type giants. This is due to the fact that convection overshoots into the formally stable outer atmospheric layers producing a notable granulation pattern in the 3D hydrodynamical models, which has a direct influence on the observable spectra and colors. Within the framework of standard 1D model atmospheres the average thermal stratification of the 3D hydro model can not be reproduced with any reasonable choice of the mixing length parameter and formulation of the turbulent pressure. The differences in individual photometric colors – in terms of 3D versus 1D – reach up to $\sim0.2$ mag, or $\Delta T_{\rm eff}\sim70$ K. We discuss the impact of full 3D hydrodynamical models on the interpretation of observable properties of late-type giants, briefly mentioning problems and challenges which need to be solved for bringing these models to a routine use within the astronomical community in 5–10 years from now.

Accumulating evidence indicates that some of ultra-luminous X-ray sources (ULXs) are intermediate mass black holes (IMBHs), but the formation process of IMBHs is unknown. One possibility is that they were formed as remnants of population III (Pop III) stars, but it has been thought that the probability of being an ULX is too low for IMBHs distributed in galactic haloes to account for the observed number of ULXs. Here we show that the number of ULXs can be explained by such halo IMBHs passing through a dense molecular cloud, if Pop III star formation is very efficient as recently suggested by the excess of the cosmic near-infrared background radiation that cannot be accounted for by normal galaxy populations. We calculate the luminosity function of X-ray sources in our scenario and find that it is consistent with observed data. Our scenario can explain that ULXs are preferentially found at outskirts of large gas concentrations in star forming regions. A few important physical effects are pointed out and discussed, including gas dynamical friction, radiative efficiency of accretion flow, and radiative feedback to ambient medium. ULXs could last for ${\sim}10^{5-6}$ yr to emit a total energy of ${\sim}10^{53}$ erg, which is sufficient to power the ionized expanding nebulae found by optical observations.

Abundance variations in globular clusters have been observed for the light elements C, N, O, Na, Al, as well as sometimes Mg. Such variations can be understood as the result of H-burning. In particular for the globular cluster M4, anticorrelations of O with Na and Al have been established from previous studies. In this study, we discuss fluorine abundances in a sample of M4 red-giants derived from infrared high-resolution spectra obtained with Pheonix on Gemini South. Our results show that fluorine now can be added to the suite of elements that are shown to vary in M4: the abundance of 19F is found to be anti-correlated with the sodium and aluminium variations. These results provide further evidence that H-burning is indeed responsible for the observed chemical inhomegeneities. Moreover, from comparisons with stellar models, tighter constraints on the mass of the polluting star in this globular cluster are extablished.

The meeting “Near Field Cosmology with Dwarf Elliptical Galaxies” covered a wide range of topics relating the general issues associated with galaxy formation and evolution as well as problems which are specific to spheroidal dwarfs. This paper summarizes these presentations in the form of an annotated guide to the presenters and their subjects. The results of the meeting demonstrate the value of focused, quantitative research on small galaxies as a way to enhance our understanding of how internal processes, cosmological foundations, and environmental conditions effect galaxy evolution.

The European southern observatory ESO is currently undertaking the ambitious task of building a “Planet Finder” instrument for the VLT. The concept for this instrument includes a 3D spectroscopic imager assisted by a very powerful eXtreme AO system. In one of the two phase-A studies for this project, we have developed a simulation software for this kind of instrument which has now been extended and applied to the case of various ELTs. In this presentation, we give results of simulations and discuss achievable signal to noise ratios and prospects for detection and characterization from young gas giants down to terrestrial type planets. ELTs of various diameters are considered as well as a set of environmental conditions.

The detection of extra-solar planets made by direct imaging is an extremely challenging goal for astronomers due to the possibility to access the physical properties of planets and not only their existence. Using 8 m class telescopes joint with dedicated techniques (such as Simultaneous Differential Imaging aiming to suppress the speckle noise) it is possible, at present, to attain detection limit of 9–11 mag at 0.5 arcsec i.e. to access 3–10 M$_{J}$ planets orbiting around young (100–200 Myr) nearby and late type stars. Searches for extra-solar planets carried out with the present technology are quite fundamental and critical not only for discovery of planets but also because it permits us to put constraints on theories of planets formation and migration. Besides, our understandings of the performances of sophisticated techniques such as the SDI is fundamental to plan new observational strategies, new generation instruments and telescopes. Speckles noise is, indeed, the main source of noise for observations in the NIR and visible and our ability in suppressing it is not so easily scaled at different parameters space. In this contribution I will present the main results that we obtained in on-going searches for planets carried out with NACO and NACO/SDI in the last years. A particular attention will be dedicated in comparing different observational strategies and in the employment of image processing techniques for recognizing, in an automatic way, planet features in deep images obtained with ground-based telescopes and AO facilities.

We present results of optical follow-up observations of candidate ultra-luminous X-ray sources (ULXs). Using Keck optical spectroscopy, 17 of the candidates from the Colbert & Ptak (2002) catalog have been identified; this is one of the largest sets of optical identifications of such objects thus far. 15 are background active galactic nuclei (AGN); 2 are foreground stars in our Galaxy. These findings are compared with background and foreground object expectations, as derived from log $N$-log $S$ relations. Also, the results are briefly discussed in terms of the spiral-galaxy/ULX connection.

We have derived Mn abundances for more than 200 stars in nineteen globular clusters. In addition, Mn abundance determinations have been made for a comparable number of halo field stars possessing an overlapping range of metallicities and stellar parameters. The primary data set was comprised of high resolution spectra previously-acquired at the McDonald, Lick and Keck Observatories. Additional data were obtained from several other investigators. Data were analyzed using synthetic spectra of the 6000 Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. Our analysis shows that over the metallicity range $-0.7>[Fe/H]-2.7$ field stars have a mean relative abundance of $<[Mn/Fe]>=-0.36$ identical to that of the nineteen globular clusters $<[Mn/Fe]>=-0.36$. Our Mn abundance results viewed in conjunction with the globular cluster Cu abundances of Simmerer et al. (2003) suggest the following possibilities: one, the production of these elements is highly metallicity-dependent or two, these elements were manufactured in the Galactic halo prior to formation of present-day globular clusters.

Modern optics focuses on photonics and quantum optics, studying individual photons and statistics of photon streams. Those can be complex and carry information beyond that recorded by imaging, spectroscopy, polarimetry or interferometry. Since [almost] all astronomy is based upon the interpretation of subtleties in the light from astronomical sources, quantum optics has the potential of becoming another information channel from the Universe. The observability of quantum statistics increases rapidly with telescope size making photonic astronomy very timely in an era of very large telescopes.

A brief description of the QuantEYE instrument proposed as a focal plane instrument for OWL is given. This instrument is dedicated to the very high speed observation of many active phenomena with a photon counting capability of up to 1GHz. The system samples the beam in 10$\times$10 subpupils, each focused on a fast photon counting detector.

This paper presents the status of the EPICS project, an Earth-like Planets Imaging Camera Spectrograph for OWL. We present the Top-Level-Requirements of the instrument and we describe the baseline of the Adaptive Optics system with optimized wave-front sensor. The expected performance in rejection of starlight in the near infrared and in the visible is given. The instruments concepts for detection and characterization of exo-planets will be briefly described. The Signal-to-Noise ratio estimation shows that Earth-like planets can be detected up to 20 pc in a reasonable amount of time. The extremely challenging requirements in terms of static residual errors and differential aberrations are discussed.

We report the serendipitous discovery of several ULX candidates in XMM-Newton observations. Such discoveries suggest that ULXs are not a negligible component of the extragalactic X-ray source population.

Despite its importance, the Galactic Bulge and its globular cluster (GC) system in particular, remain relatively unexplored due to high foreground extinction and severely crowded field populations. The new generation of high resolution IR spectrographs opens new and unique perspectives to obtain detailed abundances in the Bulge field and GCs. Using the NIRSPEC spectrograph at Keck II, high resolution, echelle spectra in the range 1.5–1.8 micron of bright giants in the Baade's window and other fields closer to the Galactic center as well as in a sample of 10 Bulge GCs have been obtained. We present the results of our abundance analysis of Fe, Al, 12C, 13C, O, and other α-elements, by using full spectral synthesis techniques.

We present here the first results (on NGC 2808 and NGC 6752) of a program that studies the anticorrelation between Na and O in a sample of Galactic Globular Clusters, using GIRAFFE spectra obtained with UVES@VLT.

In the frame of the VLT Planet-Finder project, the phase A system study has demonstrated the feasibility of an extreme adaptive optics system aimed at the direct detection of extrasolar giant planets. The main results of this study are presented in this paper.

We present the results of an on-going program for the identification and characterization of optical counterparts of Ultra-Luminous X-ray (ULX) sources. The targets have been selected from the catalogues by Colbert & Ptak (2002) and Swartz et al. (2004). A clear identification based on unambiguous optical spectral features was possible for 26 objects. A large number of objects result to be QSOs at higher redshift than the putative parent galaxy, and other ULXs seem to be associated to HII regions. In a few cases the optical counterpart results a foreground star in our galaxy. The observational program will continue to obtain a representative sample for statistical studies.

We present GALEV evolutionary synthesis models for Simple Stellar Populations (SSPs = single burst, single metallicity) like star clusters or galaxy pixels and for galaxies of various types on the basis of their respective typical star formation histories, ranging from exponentially declining on a timescale of 1Gyr for the classical elliptical model through constant for Sd galaxies, and also allowing for starbursts of various strengths occurring at various evolutionary stages. Models yield the time evolution of the stellar population in terms of color-magnitude diagrams CMDs ($U$\dots $K$), spectra (90Å…160$\mu$m) including gaseous emission in terms of lines and continuum, luminosities, colors and M/L-ratios in various filter systems (e.g. Johnson $U$\dots $K$, HST, Washington, Strömgren), and Lick indices (http://www.astro.physik.uni-goettingen.de/~galev). For galaxies, the redshift evolution is obtained from the time-evolving spectra assuming a standard cosmology (H$_0=65, \Omega_0=0.3, \Omega_{\Lambda}=0.7$) and consistently accounting for evolutionary and cosmological corrections as well as for the attenuation of light from distant galaxies by intervening HI.

We summarize the results of recent model computation for massive Asymptotic Giant Branch stars of low metallicity, whose winds are thought to be the matter from which second generation stars are born in Globular Clusters (GCs) showing abundance anomalies. The yields of these ejecta are highly uncertain, but our models in the range of masses 3.5–4.5M[odot ] can reasonably explain some of the chemical anomalies of Globular Cluster stars.

This paper will review the main astrophysical results obtained in the field of high energy Galactic sources with the INTEGRAL/IBIS Gamma-ray Imager (Ubertini et al. 2003) on-board INTEGRAL (Winkler et al. 2003), the ESA space Observatory successfully launched the 17th October 2002 from Baikonur with a Proton vehicle. In view of the high sensitivity of the two gamma ray instruments IBIS and SPI and their capability to provide at the same time image, spectra and time profiles of all the sources in their wide field of view, a key project was approved as “Core Programme” to deeply observe the Galactic Centre (GCDE) and to exploit regular scans of the whole Galaxy Plane. The major results obtained in terms of classes of high energy emitters are shortly outlined.